Long before the development of the present invention, it was known to conduct sanding with hand-held power tools.
However, hand-held power tools have a lot of unfortunate and hazardous impacts on operators, like e.g. white fingers, static electricity, repetitive work, and massive quantities of dust. Apart from this, the operators had to work from various platforms, ladders and lifts which add further to an unsafe working environment.
From EP 2590781 it is known to conduct sanding by means of an automatic abrasion arrangement comprising an abrading drum mounted on a robotic arm and where control means are used e.g. for positioning the drum on the surface upon which the drum is to abrade, to control the force by which the drum is pressed towards the surface, and to control the velocity by which the drum is moved with respect to the surface.
One of the disadvantages of this abrasion arrangement is that the contact between the surface and the drum is not measured at both ends of the drum. It is therefore uncertain if the contact between the surface and the drum actually is the same over the whole length of the drum.
Another disadvantage of this abrasion arrangement is the lack of contact wheels at both ends of the drum to control the engagement of the abrading drum in relation to the surface that has to be abraded. It is therefore uncertain to what extent the surface becomes a uniform/even treatment from the abrading drum during the abrading process, and the uncertainty becomes even bigger when the surfaces are curved or even double curved surfaces such as e.g. on a blade for a wind turbine.